The choroid is the posterior portion of the uveal tract and lies between the retina and the sclera It is darkly pigmented When the overlying sclera is thinned it is the colour of the underlying choroid which gives rise to the term 'blue sclera'
The tissue layer that sits just below the retinal pigment epithelial cells (RPE) The choroid is rich in blood vessels and connective tissue, and is a major supplier of oxygen and nutrients to the RPE and photoreceptor cells
is a part of the uvea It runs from the ciliary body around the back of the eye between the retina and the sclera (see diag p 4) It is pigmented and is mainly made up of blood vessels which supply the retina